1. Field of the Invention
The present invention relates to a water treatment apparatus and process, and more particularly to a floated biological treatment apparatus and a process for purifying refractory wastewater and raw water.
2. Description of the Prior Art
Treating wastewater in a biological manner can be classified into two categories: fixed bed operation and fluidized bed operation. The fixed bed operation suffers from clogging in the reactor, which severely affects treatment efficiency. The fluidized bed operation suffers from severe abrasion of carriers because of vigorous stirring of the carriers. This causes biofilms on the carrier surfaces unstable, which in turn affects the treated water quality.
Refractory wastewater, such as secondary treated water, contains refractory organic material that cannot be removed by the conventional secondary biological wastewater treatment. To achieve a high quality standard of effluent water, chemical treatment is generally preformed. However, this increases the cost and complicates the follow-up treatment.
Contaminated by the discharge of wastewater, the quality of raw water for drinking water often cannot meet the standards for drinking water. The main contaminating compound is ammonium nitrogen. In order to achieve the standard of raw water for drinking water, advanced treatment usually be conducted to treat the contaminated raw water. This increases the costs and wastes the resources.
The object of the present invention is to solve the above-mentioned problems and to provide a process for purifying refractory wastewater or raw water and a floated biological treatment apparatus for purifying refractory wastewater or raw water. By means of the process and apparatus of the present invention, the treatment cost for refractory organic material is reduced, treatment efficiency is enhanced, and effluent quality is improved. Moreover the hydraulic retention time required can be shortened, the treatment can be performed effectively.
To achieve the above objects, refractory wastewater or raw water is purified by treatment in a floated biological treatment apparatus. The refractory wastewater and raw water contain less than 200 mg/l of suspended solid (SS) and have a chemical oxygen demand (COD) less than 1000 mg/l and ammonium-nitrogen (NH3-N) less than 200 mg/l. The floated biological treatment apparatus includes a reactor filled with porous compressible carriers in an amount of 80 vol % to 100 vol % of the reactor volume. The carriers are adhered with microorganisms and are in a floated state.
The present invention also provides a floated biological treatment apparatus for purifying refractory wastewater or raw water. The treatment apparatus includes a supporting plate for dividing the treatment apparatus into an upper and lower portions; a liquid inlet provided at the lower portion of the treatment apparatus, from which refractory wastewater or raw water can be introduced into the apparatus; and a gas inlet provided at the lower portion of the treatment apparatus, from which gas can be introduced into the apparatus. The upper portion is the reactor that is capable of loading the porous compressible carriers in an amount of 80 vol % to 100 vol % of the reactor volume. The supporting plate is provided with a plurality of holes having a diameter less than the diameter of the carriers, such that the carriers can be regained in the upper portion of the reactor by the supporting plate without falling into the lower portion of the reactor. The upper portion of the reactor is provided with at least one top carrier blocking plate. The top carrier blocking plate has a plurality of holes with a diameter less than the diameter of the carriers, such that the carriers can be limited by the top carrier blocking plate to be retained in the reactor, and the carrier can become a floating state.